flightcrazed Posted March 3 Share Posted March 3 Hi all, working on a project that was originally designed to be an unvented attic with asphalt shingles. Plan is to change to metal, however the underlayment (Titanium UDL50) has already been laid and is only Class A under asphalt. I've found that Versashield can bring metal to Class A but not intended for unvented assembly. Anyone know of another product that could be laid on top of UDL50 to reach Class A for metal? I've found Atlas FR10 but all the documentation seem to support a commercial roofing system. Much appreciated! Link to comment Share on other sites More sharing options...
Hammer7 Posted March 3 Share Posted March 3 There are CSI folks that specialize in commercial roofing applications if you don't find answers here. You can get some local names from your local commercial supply house. 1 Link to comment Share on other sites More sharing options...
Gawdzira Posted March 3 Share Posted March 3 Would Denseshield work? I am not speaking from experience but seems like the right type of product. Link to comment Share on other sites More sharing options...
flightcrazed Posted March 4 Author Share Posted March 4 looks like the densdeck version might work...at least it's been tested by some metal vendors. i was hoping to find something a little simpler to install like 30# felt or similar Link to comment Share on other sites More sharing options...
Gawdzira Posted March 4 Share Posted March 4 I am going to look into this as I have a similar situation. I am doing a double roof system on my current project. The first sheathing layer is Zip and then 2x4's on edge to get my overhang and fill that cavity with closed cell spray foam. Metal standing seam over the top of the next sheathing layer. Link to comment Share on other sites More sharing options...
flightcrazed Posted March 4 Author Share Posted March 4 Awesome, let me know what you find. i'm still digging around as well and will let you know what i come up with Link to comment Share on other sites More sharing options...
Alaskan_Son Posted March 5 Share Posted March 5 On 3/3/2025 at 11:42 AM, flightcrazed said: Hi all, working on a project that was originally designed to be an unvented attic with asphalt shingles. Plan is to change to metal, however the underlayment (Titanium UDL50) has already been laid and is only Class A under asphalt. I've found that Versashield can bring metal to Class A but not intended for unvented assembly. Anyone know of another product that could be laid on top of UDL50 to reach Class A for metal? I've found Atlas FR10 but all the documentation seem to support a commercial roofing system. Much appreciated! Because of its low perm rating, I don't believe Titanium UDL50 is designed for use over an unvented attic either. If the builder was okay with that, then I would think Versashield would be just fine as well--if not better. I think the real problem is the perm rating of any product going over an unvented assembly and the manufacturers resistance to taking on any liability whether actual or perceived. I believe UDL50 has a perm rating of around 0.05 whereas Versashield has a perm rating of 3 at a minimum. Major difference and a major improvement in breathabiliy over the UDL50. Either way, if you really want to do it by the book and decide to go with DensDeck or some other similar fire resistant paneling/sheathing, make sure not to defeat the whole purpose by putting another non breathable roofing layer over the top of it. Link to comment Share on other sites More sharing options...
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